665 2002-02-23 17:50:41 +0300 read builtin doesn\'t work if its input comes from a pipe 2003-08-25 15:18:28 +0400 1 1 4 Development Sisyphus bash unstable all Linux CLOSED NOTABUG P4 major --- 1 vanyaz placeholder glebfm ldv placeholder vt oldest_to_newest 636 0 vanyaz 2002-02-23 17:50:41 +0300 This command prints an empty line in bash-2.05-alt4: a=\"\"; echo A | read a; echo $a but it should print a line with A. --- --- Strange that adding braces helps, these commands print A: a=\"\"; echo A | { a=\"\"; read a; echo $a; } a=\"\"; echo A | ( a=\"\"; read a; echo $a; ) Reading from the keyboard and not a pipe also works correctly. All the three commands mentioned here work the same right way in zsh. 3328 1 ldv 2002-03-22 17:49:28 +0300 See /usr/share/doc/bash-2.05/FAQ: E4) If I pipe the output of a command into `read variable\', why doesn\'t the output show up in $variable when the read command finishes? This has to do with the parent-child relationship between Unix processes. It affects all commands run in pipelines, not just simple calls to `read\'. For example, piping a command\'s output into a `while\' loop that repeatedly calls `read\' will result in the same behavior. Each element of a pipeline runs in a separate process, a child of the shell running the pipeline. A subprocess cannot affect its parent\'s environment. When the `read\' command sets the variable to the input, that variable is set only in the subshell, not the parent shell. When the subshell exits, the value of the variable is lost. 6693 2 ldv 2002-03-22 17:49:28 +0300 See /usr/share/doc/bash-2.05/FAQ: E4) If I pipe the output of a command into `read variable\', why doesn\'t the output show up in $variable when the read command finishes? This has to do with the parent-child relationship between Unix processes. It affects all commands run in pipelines, not just simple calls to `read\'. For example, piping a command\'s output into a `while\' loop that repeatedly calls `read\' will result in the same behavior. Each element of a pipeline runs in a separate process, a child of the shell running the pipeline. A subprocess cannot affect its parent\'s environment. When the `read\' command sets the variable to the input, that variable is set only in the subshell, not the parent shell. When the subshell exits, the value of the variable is lost.